PDA is terminal having portability not available from PC (personal computer), usage irrespective of place, and assistant role-play of personal information management, providing a more user-friendly computer environment through its small size, convenient portability, and interoperability with PC and thus its range of usage getting expanded.
PDA constitutes ROM (read only memory) with a basic program embedded for its own drive, flash memory for driving an operating system, RAM (read access memory) driving an application and performing the role of storage media, liquid crystal display for showing the proceeding status of an application, and input/output terminal for inputting/outputting the external of application and data, and the like. The operating system is usually loaded in the flash memory.
Such PDA substitutes for the function of an existing paper diary or electronic note and enables to e-mail or reserve appointment time, alarm, etc. by various interoperability means. Further, it is possible to install and execute a variety of programs being employed in PC. PDA is securing its position as an information-oriented solution device for corporate plus role-playing as a wireless Internet assistant device such as email and web browsing.
Likewise PC, a variety of applications for PDA now are selling according to the operating system and central processing unit (CPU). However, PDA applications are usually small in size, and weak in illegal distribution in view of its own structure. In the case of using a general encoding method or authentication procedure being used in a PC DP, since storage capacity and memory used are extremely restricted and performance speed also goes down, it is difficult to perform encoding or authentication normally. Besides, since each serial number of PDA cannot be recognized and the type and operating system of PDA are not unified, the encoding module or authentication procedure available in PDA in a real time is extremely restricted.
In particular, owing to the development of Internet there are various opportunities to obtain applications (digital contents having various types including application), whereas a demand for protection technology for applications rapidly grows due to easy duplicate and circulation. Hence, as an alternative, digital rights management (DRM) of protecting, securing, and managing the digital contents, that is, technology of preventing illegal use of the digital contents being circulated, continuing to protect and manage right and profit of copyright holders and license holders which are originated from a use of the protected digital contents, and technology in service area are under development.
The applicant suggested a variety of ways to protect right of the copyright holders for their works through Internet in the form of on-line as well as off-line, which have been filed as several patent applications including Korean Patent Application No. 2001-23562. However, the above ways of protection are mostly focused on the digital contents based on PC.
However, recently the digital contents are provided or used through PC as well as the digital contents in various types of text, music, image, software, etc. are provided by means of a personal digital assistant, PDA. Differently from such current, a specific method of protecting an application being performed in PDA is insufficient and a couple of methods are recently suggested.
Of these methods, a method of protecting applications being performed in PDA is disclosed in Korean Patent Laid-Open No. 2001-99412 (entitled: software distribution system for PDA) as illustrated in FIG. 1. The above prior art illustrated in FIG. 1 saves a program (10a) to be executed in the PDA (20) in a separate removable memory card (10) simultaneously with saving an authentication data key in the memory card (10) so as to prevent it from being copied to other medium before transmitting an authentication key to authenticating server (50) on Internet in the PDA (20). It discloses a method of transmitting an install key disabling the locking state of the application stored in the memory card (10) from the authenticating server (50) to PDA (20) and thus employing the application (10a) of the memory card (10), in the case that the authentication key is authenticated by examining its integrity in the authenticating server.
However, in the above prior art, a memory card should be used inconveniently in order to install application and a hardware-like port or interface to which a memory card is connected externally should be separately required, whereby the expenses are considerably increased and it is inconvenient in installing software and upgrading, taking into consideration that software are recently distributed through Internet.
In order to improve the problem of using a separate memory card as described above, Korean Patent Laid-Open No. 2001-106325 (entitled: method and system for providing e-book contents service for wireless PDA having function of user authentication for digital copyright management service), as illustrated in FIG. 2, discloses that e-book contents are downloaded through communications between PDA (20) and authenticating server (50) and the e-book contents selected by using an authentication key corresponding to the user registration information are decoded in the PDA (20) so as to be used only by a particular user, thereby preventing e-book contents from being illegally circulated.
However, the operating speed of PDA is too slow in applying to the above technology of encoding the digital contents, e-book, and decoding it during the execution of a specific application so as to read the corresponding e-book. And since PDA generally executes in a storage area, it is very difficult to apply to such technology due to its operating system. Further, the authentication key is generated and managed based on the user's PDA information where the PDA information indicates PDA system information such as CPU size of PDA, memory size, etc. Hence, it is difficult to substantially regard it as unique information to specify PDA. That is, if the number of PDA user connecting to an authenticating server increases, it could be difficult to regard the authentication key as a unique key having unique characteristic based on users. These are related to PDA's own basic problem, and the above prior art has a problem of failing to exactly recognize the characteristic of PDA.